Charles Mingus: postman

Yesterday's Trivia: "When the trio came back from Hawaii, I remembered a bass player who had subbed for me in San Francisco when I was working a tour with Billie Holiday. I tried to find him. and couldn’t locate him. Eventually I found him. He was carrying mail in Los Angeles. So that’s how ????? joined me—after I convinced him to give up the mail route. That was really when it started to go."

Who said that and who is the bass player?

Red Norvo said it - about Charles Mingus - who had worked as a postman.- and